This invention relates generally to motion picture photography and, more particularly, to an improved transducer backup arrangement for a multipurpose sound motion picture film handling cassette.
The present invention is directed to a spring and film backup support arrangement against which a film strip is biased by a recording/playback transducer in connection with a photographic film cassette from which the film strip need not be removed during the exposure, processing and projection operations and, more particularly, to film cassettes of the type which include internally programmed film processing systems. Exemplary of such systems are those described in the commonly assigned U.S. Pat. No. 3,785,727 of John F. Batter Jr., et al. As described in the above-referenced patent, a motion picture system has been devised wherein a supply of photographic film contained in a cassette can be exposed in a camera adapted to receive the cassette and then subsequently the cassette is loaded into a projector apparatus which first subjects the cassette to a sequence of operations intended to process the film strip to a viewable condition and then subsequently projects the developed recorded images.
It has also been proposed that the film strip in addition to carrying a photosensitive area, carry a magnetic sound track affixed to or formed as a part thereof. Such film strip and magnetic sound track combinations have been marketed for motion picture cameras and projectors and are commonly used within the photographic art. Whether such films have the magnetic track affixed to or formed as a part of it, recording may be carried out in either the camera or, subsequent to exposure, in a projector type arrangement in which "fill-in" or background comments are provided. When such recording and playback occurs, both a magnetic transducer head and a constant speed drive capstan must be introduced through the cassette structure in order to contact the magnetic track portion of the film strip. A constant speed drive capstan is employed for moving the film strip and magnetic track past the transducer head at a constant speed in order to achieve a good quality of sound recording.
In addition to constant speed of the sound track, it is also extremely important that the contact between the sound track and the recording/playback transducer be extremely good in order to provide quality sound at all desired frequency levels. In order to accomplish this, resilient support means are typically provided behind the film strip in the region of contact with the transducer thereby urging the film strip into contact with the transducer. In a typical arrangement, a resilient means imparts a force to a film strip backup structure which engages the entire backside of the film strip and urges the entire film strip into contact with the transducer head. Such an arrangement imparts a significant drag upon the film strip when the cassette is operating in the sound mode and accordingly requires the cassette structure and the drive means for advancing the film through the cassette to be capable of moving the film strip at the desired speeds with this additional significant drag upon the film.